Re: EDB builds Postgres 13 with an obsolete ICU version

On Fri, Aug 14, 2020 at 3:00 PM Bruce Momjian <bruce@momjian.us> wrote:

On Tue, Aug 11, 2020 at 02:58:30PM +0200, Magnus Hagander wrote:
> On Tue, Aug 4, 2020 at 11:42 AM Dave Page <dpage@pgadmin.org> wrote:
>     That would require fairly large changes to the installer to allow it to
>     login to the database server (whether that would work would be dependent on
>     how pg_hba.conf is configured), and also assumes that the ICU ABI hasn't
>     changed between releases. It would also require some hacky renaming of
>     DLLs, as they have the version number in them.
>
> I assumed it had code for that stuff already. Mainly because I assumed it
> supported doing pg_upgrade, which requires similar things no?

While pg_upgrade requires having the old and new cluster software in
place, I don't think it helps allowing different ICU versions for each
cluster. 

Depends on where they are installed (and disclaimer, I don't know how the windows installers do that). But as long as the ICU libraries are installed in separate locations for the two versions, which I *think* they are or at least used to be, it shouldn't have an effect on this in either direction.

That argument really only holds for different versions, not for different clusters of the same version. But I don't think the installers (natively) supports multiple clusters of the same version anyway.

The tricky thing is if you want to allow the user to *choose* which ICU version should be used with postgres version <x>.  Because then the user might also expect an upgrade-path wherein they only upgrade the icu library on an existing install...

 

I guess you can argue that if you know the user is _not_ going
to be using pg_upgrade, then a new ICU version should be used for the
new cluster.

Yes, that's exactly the argument I meant :) If the user got the option to "pick version of ICU: <old>, <new>", with a comment saying "pick old only if you plan to do a pg_upgrade based upgrade of a different cluster, or if this instance should participate in replication with a node using <old>", that would probably help for the vast majority of cases. And of course, if the installer through other options can determine with certainty that it's going to be running pg_upgrade for the user, then it can reword the dialog based on that (that is, it should still allow the user to pick the new version, as long as they know that their indexes are going to need reindexing)